Hearing devices such as smart phones and hearing aids typically include an earbud that is adapted to be adjacent to or inserted into an ear canal of a user. Such earbuds typically include one of two different types of configurations. The first configuration is an open design where acoustic information from the hearing device can be directed into the ear canal of a user along with ambient sound from the user's environment. For earbuds that are at least partially inserted into the ear canal, one or more vents may be formed in the earbud that allow the ambient sound to be transmitted from the user's environment into the ear canal and received by the user. The second configuration is an occluded design that also delivers acoustic information from the hearing device into the ear canal of the user while substantially or completely sealing the ear canal such that most or all ambient sound from the user's environment does not reach the ear canal.
Hearing aids that include one or more of these earbuds are electroacoustic devices that amplify sound for the user to correct hearing deficits as measured by audiometry, usually with the primary purpose of making speech more intelligible. Certain types of hearing aids utilize the earbud that is placed in the user's ear canal that conducts the sound produced by the hearing aid's receiver (i.e., loudspeaker). A receiver-in-canal (RIC) hearing aid has a small body that sits behind the ear and houses the hearing aid's microphone and audio processing circuitry. The receiver of the RIC hearing aid is attached to the earbud inside the ear and is connected to the body of the hearing aid by a slim tube that houses the receiver wiring. Other types of hearing aids may incorporate the receiver into the body behind the ear that then conducts sound to an earbud inside the ear via an audio tube.